Metamath Proof Explorer


Theorem 4pos

Description: The number 4 is positive. (Contributed by NM, 27-May-1999)

Ref Expression
Assertion 4pos 0 < 4

Proof

Step Hyp Ref Expression
1 3re 3
2 1re 1
3 3pos 0 < 3
4 0lt1 0 < 1
5 1 2 3 4 addgt0ii 0 < 3 + 1
6 df-4 4 = 3 + 1
7 5 6 breqtrri 0 < 4